Photoelectric conversion device and manufacturing method thereof

ABSTRACT

A photoelectric conversion device of an embodiment includes: a first photoelectric conversion part including a first transparent electrode, a first organic active layer, and a first counter electrode; and a second photoelectric conversion part including a second transparent electrode, a second organic active layer, and a second counter electrode, which are provided on a transparent substrate. A conductive layer is formed on a partial region, of the second transparent electrode, which is adjacent to the first transparent electrode. The first counter electrode and the second transparent electrode are electrically connected by a connection part including a groove formed from a surface of the second organic active layer to reach an inside of the conductive layer and a part of the first counter electrode filled in the groove.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2015-056141, filed on Mar. 19, 2015; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments disclosed herein relate generally to a photoelectricconversion device and a manufacturing method thereof.

BACKGROUND

The application of organic semiconductors to photoelectric conversiondevices such as a photovoltaics, a light emitting element, and aphotosensor is being expected. Using an organic semiconductor as aforming material of an active layer of a photovoltaics and the likemakes it possible to employ an inexpensive coating method for formingthe active layer and the like, and thus enables a great reduction of aformation cost of the active layer and the like. Because of thesepoints, an organic photovoltaics and an organic/inorganic hybridphotovoltaics which use an organic semiconductor are expected as anext-generation photovoltaics that cost low and are harmless.

Cells forming a photovoltaic module each have a structure in which anactive layer is sandwiched by a transparent electrode and a counterelectrode. A transparent electrode on a practical level does not havesufficient conductivity, and accordingly efficiency for extractinggenerated electric charges deteriorates as a cell area is increased. Asa forming material of the transparent electrode, a conductive metaloxide, a conductive polymer, a carbon material, or the like is used, andfurther, a material in which a metal nanowire or the like is compoundedwith any of these is used. In a photovoltaic module, generally, aplurality of strip-shaped cells are arranged and the plural cells areconnected in series.

A photovoltaic module having a plurality of cells is formed by thefollowing method, for instance. Transparent electrodes of the respectivecells are formed on a transparent substrate. An organic active layer isformed on the whole surface of the plural transparent electrodes bycoating. Part of the organic active layer is scribed, whereby groovesfrom which the transparent electrodes are exposed are formed. Counterelectrodes are formed on the organic active layer having the scribegrooves so as to correspond to the respective cells. At this time, inthe scribe groove, the counter electrode of the adjacent cell is filled,so that the counter electrode of the adjacent cell is electricallyconnected with the transparent electrode exposed in the scribe groove.

The scribing of the organic active layer is executed by mechanicalscribing using a cutting tool, for instance. In a case where aconductive metal oxide is used as the transparent electrode, a hardtransparent conductive oxide layer exists under the soft organic activelayer, and thus at the time of the mechanical scribing of the organicactive layer, the organic active layer is likely to remain on theconductive metal oxide. The organic active layer, if remaining on theconductive metal oxide, increases electrical resistance between thetransparent electrode and the counter electrode of the adjacent cell,resulting in deterioration of power conversion efficiency. Increasing ascribing pressure so as to prevent the organic active layer fromremaining is likely to cause a crack or the like in the transparentconductive oxide layer. In a case where a conductive polymer is used asthe transparent electrode, the transparent electrode has the samesoftness as that of the organic active layer, which makes it difficultto selectively scribe the organic active layer so that the conductivepolymer remains without the organic active layer remaining.

The above circumstances have given rise to a demand for an art toimprove electrical connectivity between the adjacent cells(photoelectric conversion parts) by achieving both the prevention of theorganic active layer from remaining on the transparent electrodes andthe prevention of breakage of the transparent electrodes at the time ofthe mechanical scribing of the organic active layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a schematic structure of aphotoelectric conversion device according to an embodiment.

FIG. 2 is an enlarged sectional view illustrating a photoelectricconversion part in the photoelectric conversion device illustrated inFIG. 1.

FIG. 3A to FIG. 3C are sectional views schematically illustrating amanufacturing method of the photoelectric conversion device illustratedin FIG. 1.

FIG. 4A to FIG. 4D are sectional views illustrating a connection step ofthe photoelectric conversion parts in the manufacturing method of thephotoelectric conversion device of the embodiment and the structure of aconnection part.

FIG. 5A to FIG. 5C are plane views illustrating the connection step ofthe photoelectric conversion parts in the manufacturing method of thephotoelectric conversion device of the embodiment.

FIG. 6 is a sectional view illustrating another structure example of theconnection part in the photoelectric conversion device of theembodiment.

DETAILED DESCRIPTION

According to one embodiment, there is provided a photoelectricconversion device including: a transparent substrate; a firstphotoelectric conversion part including a first transparent electrodeprovided on the transparent substrate, a first organic active layerdisposed on the first transparent electrode, and a first counterelectrode disposed on the first organic active layer; a secondphotoelectric conversion part including a second transparent electrodedisposed on the transparent substrate adjacently to the firsttransparent electrode and electrically insulated from the firsttransparent electrode, a conductive layer formed on a partial region ofthe second transparent electrode, the partial region being adjacent tothe first transparent electrode, a second organic active layer disposedon the second transparent electrode, and a second counter electrodedisposed on the second organic active layer; and a connection partincluding a groove formed from a surface of the second organic activelayer to reach an inside of the conductive layer and a part of the firstcounter electrode filled in the groove and which electrically connectsthe first counter electrode and the second transparent electrode via theconductive layer.

Hereinafter, a photoelectric conversion device of an embodiment and amanufacturing method thereof will be described with reference to thedrawings. Note that, in each embodiment, substantially the sameconstituent parts are denoted by the same reference signs and adescription thereof will be partly omitted in some case. The drawingsare schematic, and a relation of thickness and planar dimension, athickness ratio among parts, and so on are sometimes different fromactual ones. Terms indicating up and down directions and so on in thedescription indicate relative directions when a surface, of thelater-described transparent substrate, where to form the photoelectricconversion parts is defined as an up direction, unless otherwise noted,and they are sometimes different from actual directions based on agravitational acceleration direction.

FIG. 1 illustrates a schematic structure of the photoelectric conversiondevice of the embodiment. The photoelectric conversion device 1illustrated in FIG. 1 includes a transparent functioning as a supportsubstrate and a plurality of photoelectric conversion parts 3 (3A, 3B,3C) disposed on the transparent substrate 2. The photoelectricconversion parts 3 each include a transparent electrode 4 (4A, 4B, 4C),a photoelectric conversion layer 5 (5A, 5B, 5C), and a counter electrode6 (6A, 6B, 6C) which are formed on the transparent substrate 2 in theorder mentioned.

The transparent substrate 2 is formed of a material having a lighttransmitting property and insulation performance. As the constituentmaterial of the transparent substrate 2, an inorganic material such asnon-alkali glass, quartz glass, or sapphire, or an organic material suchas polyethylene (PE), polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), polyimide, polyamide, polyamide-imide, or a liquidcrystal polymer is used. For example, the transparent substrate 2 may bea rigid substrate formed of an inorganic material or an organicmaterial, or may be a flexible substrate formed of an organic materialor a very thin inorganic material.

In the photoelectric conversion device 1 of the embodiment, thephotoelectric conversion layer 5 is irradiated with light through thetransparent substrate 2 and the transparent electrode 4. Or, lightgenerated in the photoelectric conversion layer 5 is emitted through thetransparent substrate 2 and the transparent electrode 4. In a case wherethe photoelectric conversion device 1 is a photovoltaics, chargeseparation is caused by the light irradiating the photoelectricconversion layer 5, so that electrons and holes are generated. Out ofthe electrons and the holes generated in the photoelectric conversionlayer 5, for example, the electrons are collected in the transparentelectrode 4, and the holes are collected in the counter electrode 6. Thefunctions of the transparent electrode 4 and the counter electrode 6 maybe reversed. Hereinafter, these parts will be described.

The transparent electrode 4 is formed of a material having a lighttransmitting property and conductivity. As the constituent material ofthe transparent electrode 4, a conductive metal oxide such as indiumoxide, zinc oxide, tin oxide, indium tin oxide (ITO), fluorine-doped tinoxide (FTO), gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide(AZO), indium-zinc oxide (IZO), and indium-gallium-zinc oxide (IGZO); aconductive polymer such as poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS); and acarbon material such as graphene are usable. A material in which a nanoconductive material such as a silver nano wire, a gold nano wire, or acarbon nanotube is mixed in any of the aforesaid materials is alsousable. Further, the transparent electrode 4 may be a film stack of alayer formed of any of the aforesaid materials and a metal layer formedof metal such as gold, platinum, silver, copper, cobalt, nickel, indium,or aluminum, or an alloy containing any of these metals, within a rangecapable of maintaining the light transmitting property. The transparentelectrode 4 is formed by, for example, a vacuum deposition method, asputtering method, an ion plating method, a CVD method, a sol gelmethod, a plating method, a coating method, or the like.

A thickness of the transparent electrode 4 is not particularly limited,but is preferably not less than 10 nm nor more than 1 μm, and morepreferably not less than 30 nm nor more than 300 nm. When the filmthickness of the transparent electrode 4 is too thin, sheet resistancebecomes high. When the film thickness of the transparent electrode 4 istoo thick, light transmittance decreases, and further flexibilitydecreases, so that a crack or the like is likely to occur due to amechanical stress. It is preferable to select the film thickness of thetransparent electrode 4 so that high light transmittance and low sheetresistance are both obtained. The sheet resistance of the transparentelectrode 4 is not particularly limited, but is generally 1000Ω/□ orless, more preferably 500Ω/□ or less, and still more preferably 200Ω/□or less. In a case of a current driven type such as a photovoltaics anda light emitting element, 50Ω/□ or less is more preferable.

The photoelectric conversion layer 5 has an organic active layer 51, afirst intermediate layer (first buffer layer) 52 disposed between thetransparent electrode 4 and the organic active layer 51, and a secondintermediate layer (second buffer layer) 53 disposed between the organicactive layer 51 and the counter electrode 6, as illustrated in FIG. 2.The intermediate layers 52, 53 are disposed when necessary, and in somecase, both or one of the intermediate layers 52, 53 may be omitted. Thelayers 51, 52, 53 forming the photoelectric conversion layer 5 areappropriately selected according to a device (a photovoltaics, a lightemitting element, a photosensor, or the like) to which the photoelectricconversion device 1 is applied. Hereinafter, a case where thephotoelectric conversion device 1 is used as a photovoltaics will bemainly described, but the photoelectric conversion device 1 of theembodiment is applicable to a light emitting element, a photosensor, andthe like.

In a case where the photoelectric conversion device 1 of the embodimentis applied to an organic photovoltaics, the organic active layer 51contains, for example, a p-type semiconductor and an n-typesemiconductor. As the p-type semiconductor in the organic active layer51, a material having an electron donating property is used, and as then-type semiconductor, a material having an electron accepting propertyis used. The p-type semiconductor and the n-type semiconductor formingthe organic active layer 51 both may be organic materials or one of themmay be an organic material.

As the p-type semiconductor contained in the organic active layer 51,polythiophene and its derivative, polypyrrole and its derivative, apyrazoline derivative, an arylamine derivative, a stilbene derivative, atriphenyldiamine derivative, oligothiophene and its derivative,polyvinyl carbazole and its derivative, polysilane and its derivative, apolysiloxane derivative having aromatic amine at a side chain or a mainchain, polyaniline and its derivative, a phthalocyanine derivative,porphyrin and its derivative, polyphenylene vinylene and its derivative,polythienylene vinylene and its derivative, and the like are usable.These materials may be used in combination, or a mixture or a compoundof any of these materials and another material may be used.

As the p-type semiconductor, polythiophene being a conductive polymerhaving a π-conjugated structure and its derivative are preferably used.Polythiophene and its derivative have excellent stereoregularity and arerelative high in solubility in a solvent. Polythiophene and itsderivative are not particularly limited, provided that they are each acompound having a thiophene framework. Specific examples ofpolythiophene and its derivative are: polyalkylthiophene such aspoly(3-methylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene),poly(3-octylthiophene), and poly(3-decylthiophene); polyarylthiophenesuch as poly(3-phenylthiophene) and poly(3-(p-alkylphenylthiophene));polyalkylisothionaphthene such as poly(3-butylisothionaphthene),poly(3-hexylisothionaphthene), poly(3-octylisothionaphthene), andpoly(3-decylisothionaphthene); polyethylenedioxythiophene;poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT); poly[4,8-bis{(2-ethylhexyl)oxy}benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-lt-alt-3-fluoro-2-{(2-ethylhexyl)carbonyl)}thieno[3,4-b]thiophene-4,6-diyl](PTB7); and so on.

As the n-type semiconductor contained in the organic active layer 51,fullerene, a fullerene derivative, or the like is used. The fullerenederivative may be any, provided that it has a fullerene framework.Examples of the fullerene and the fullerene derivative are fullerenesuch as C₆₀, C₇₀, C₇₆, C₇₈, and C₈₄, fullerene oxide being any of thesefullerenes whose carbon atoms at least partly are oxidized, a compoundin which part of carbon atoms of a fullerene framework is modified byoptional functional groups, a compound in which these functional groupsare bonded to form a circle, and so on.

Examples of the functional group used for the fullerene derivative are:a hydrogen atom; a hydroxyl group; a halogen atom such as a fluorineatom and a chlorine atom; an alkyl group such as a methyl group and anethyl group; an alkenyl group such as a vinyl group; a cyano group; analkoxy group such as a methoxy group and an ethoxy group; an aromatichydrocarbon group such as a phenyl group and a naphthyl group; anaromatic heterocyclic group such as a thienyl group and a pyridyl group;and so on. Specific examples of the fullerene derivative are fullerenehydride such as C₆₀H₃₆ and C₇₀H₃₆, fullerene oxide being oxidized C₆₀and C₇₀, a fullerene metal complex, and the like. As the fullerenederivative, [6,6]phenylC₆₁butyric acid methylester (PC60BM),phenylC₇₁butyric acid methylester (PC70BM), bis-indeneC₆₀ (60ICBA), orthe like is preferably used.

The organic active layer 51 has a bulk hetero junction structurecontaining a mixture of a p-type semiconductor material and an n-typesemiconductor material, for instance. The organic active layer 51 of thebulk hetero junction type has a microphase-separated structure of thep-type semiconductor material and the n-type semiconductor material. Inthe organic active layer 51, a p-type semiconductor phase and an n-typesemiconductor phase are separated from each other and form a pn junctionon a nano meter order. When the organic active layer 51 absorbs light,positive charges (holes) and negative charges (electrons) are separatedon an interface of these phases and they are transported to theelectrodes 4, 6 through the respective semiconductors. The organicactive layer 51 of the bulk hetero junction type is formed by applying asolution in which the p-type semiconductor material and the n-typesemiconductor material are dissolved in a solvent, on the transparentsubstrate 2 having the transparent electrode 4 and so on. A thickness ofthe organic active layer 51 is not particularly limited, but ispreferably 10 nm to 1000 nm.

In a case where the photoelectric conversion device 1 is applied to anorganic/inorganic hybrid photovoltaics, the organic active layer 51includes, for example, an organic/inorganic hybrid perovskite compound.An example of the organic/inorganic hybrid perovskite compound is acompound having a composition expressed by CH₃NH₄MX₃ (M is at least oneelement selected from lead and tin, and X is at least one elementselected from iodine, bromine, and chlorine). Examples of a method offorming the organic active layer 51 are a method of depositing theaforesaid perovskite compound or its precursor by vacuum deposition, anda method of applying a solution in which the perovskite compound or itsprecursor is dissolved in a solvent, followed by heating and drying. Anexample of the precursor of the perovskite compound is a mixture ofmethylammonium halide and lead halide or tin halide. The thickness ofthe organic active layer 51 is not particularly limited but ispreferably 10 nm to 1000 nm.

In a case where the electrons generated in the photoelectric conversionlayer 5 are collected in the transparent electrode 4, the firstintermediate layer (first buffer layer) 52 is formed of a materialcapable of selectively and efficiently transporting the electrons. Asthe constituent material of the first intermediate layer 52 functioningas an electron transport layer, an inorganic material such as zincoxide, titanium oxide, or gallium oxide, or an organic material such aspolyethyleneimine or its derivative is used. The first intermediatelayer 52 is formed by, for example, a vacuum deposition method, asputtering method, an ion plating method, a sol gel method, a platingmethod, a coating method, or the like. A thickness of the firstintermediate layer 52 is preferably not less than 0.05 nm nor more than200 nm, and more preferably not less than 0.1 nm nor more than 50 nm.

In a case where the holes generated in the photoelectric conversionlayer 5 are collected in the counter electrode 6, the secondintermediate layer (second buffer layer) 53 is formed of a materialcapable of selectively and efficiently transporting the holes. As theconstituent material of the second intermediate layer 53 functioning asa hole transport layer, an inorganic material such as vanadium oxide,tantalum oxide, or molybdenum oxide, or an organic material such aspolythiophene, polypyrrole, polyacetylene,triphenylenediaminepolypyrrol, polyaniline, or a derivative of any ofthese is used. The second intermediate layer 53 is formed by, forexample, a vacuum deposition method, a sputtering method, an ion platingmethod, a sol gel method, a plating method, a coating method, or thelike. A thickness of the second intermediate layer 53 is preferably notless than 0.05 nm nor more than 200 nm, and more preferably not lessthan 0.1 nm nor more than 50 nm.

The counter electrode 6 is formed of a material having conductivity, andin some case, having a light transmitting property. As the constituentmaterial of the counter electrode 6, metal such as platinum, gold,silver, copper, nickel, cobalt, iron, manganese, tungsten, titanium,zirconium, tin, zinc, aluminum, indium, chromium, lithium, sodium,potassium, rubidium, cesium, calcium, magnesium, barium, samarium, orterbium, an alloy containing any of these, a conductive metal oxide suchas an indium-zinc oxide (IZO), a conductive polymer such as PEDOT/PSS,or a carbon material such as graphene is used, for example. A materialin which a nano conductive material such as a silver nanowire, a goldnanowire, or a carbon nanotube is mixed in any of the aforesaidmaterials is also usable.

The counter electrode 6 is formed by, for example, a vacuum depositionmethod, a sputtering method, an ion plating method, a sol gel method, aplating method, a coating method, or the like. A thickness of thecounter electrode 6 is not particularly limited, but preferably is notless than 1 nm nor more than 1 μm. When the film thickness of thecounter electrode 6 is too thin, resistance becomes too high, which maymake it impossible to sufficiently transmit the generated electriccharges to an external circuit. When the thickness of the counterelectrode 6 is too thick, its film formation takes a long time andaccordingly a material temperature increases, which may damage theorganic active layer 51. Sheet resistance of the counter electrode 6 isnot particularly limited, but is preferably 500Ω/□ or less, and morepreferably 200Ω/□ or less. In a case of a device of a current driventype such as a photovoltaics and a light emitting element, the sheetresistance is still more preferably 50Ω/□ or less.

Manufacturing steps of the photoelectric conversion device 1 in theembodiment will be roughly described with reference to FIG. 3A to FIG.3C. As illustrated in FIG. 3A, the transparent electrodes 4A, 4B, 4Ccorresponding to the plural photoelectric conversion parts 3A, 3B, 3Care formed on the transparent substrate 2. The transparent electrode 4Bis formed so as to be adjacent to the transparent electrode 4A and so asto be electrically insulated from the transparent electrode 4A.Similarly, the transparent electrode 4C is formed so as to be adjacentto the transparent electrode 4B and so as to be electrically insulatedfrom the transparent electrode 4B. A photoelectric conversion layer 5Xis formed above the transparent substrate 2 so as to cover thesetransparent electrodes 4A, 4B, 4C. The photoelectric conversion layer 5Xis formed on the whole surface so as to cover all the transparentelectrodes 4A, 4B, 4C.

Next, as illustrated in FIG. 3B, the photoelectric conversion layer 5Xis scribed, whereby grove portions 11A, 11B are formed so that thephotoelectric conversion layer 5X is divided into a plurality of partscorresponding to the respective photoelectric conversion parts 3A, 3B,3C. The groove portions 11A, 11B dividing the photoelectric conversionlayer 5X are formed by, for example, mechanical scribing. By dividingthe photoelectric conversion layer 5X into the plural parts by thegroove portions 11A, 11B, the photoelectric conversion layers 5A, 5B, 5Ccorresponding to the plural photoelectric conversion parts 3A, 3B, 3Care formed. The dividing groove portions 11A, 11B are regions where toform connection parts for electrically connecting the counter electrodes6A, 6B of the photoelectric conversion parts 3A, 3B with the transparentelectrodes 4B, 4C of the adjacent photoelectric conversion parts 3B, 3C.

As illustrated in FIG. 3C, the counter electrodes 6A, 6B, 6Ccorresponding to the plural photoelectric conversion parts 3A, 3B, 3Care formed on the photoelectric conversion layers 5A, 5B, 5Crespectively. In forming the counter electrodes 6A, 6B of thephotoelectric conversion parts 3A, 3B, parts (counter electrodematerials) 6 a, 6 b of the counter electrodes 6A, 6B are filled in thegroove portions 11A, 11B provided between the photoelectric conversionparts 3A, 3B and the adjacent photoelectric conversion parts 3B, 3C. Inthis manner, the counter electrodes 6A, 6B of the photoelectricconversion parts 3A, 3B are electrically connected with the transparentelectrodes 4B, 4C of the adjacent photoelectric conversion parts 3B, 3Cvia the counter electrode materials 6 a, 6 b filled in the grooveportions 11A, 11B.

Incidentally, in a conventional manufacturing step, in order toelectrically connect the counter electrodes 6A, 6B of the photoelectricconversion parts 3A, 3B with the transparent electrodes 4B, 4C of theadjacent photoelectric conversion parts 3B, 3C, surfaces of thetransparent electrodes 4B, 4C are exposed in the groove portions 11A,11B. The groove portions 11A, 11B are formed by mechanical scribingusing a cutting tool or the like. In mechanically scribing thephotoelectric conversion layer 5X, if a pressure with which the surfacesof the transparent electrodes 4B, 4C are surely exposed is applied, acrack or the like is likely to occur in the transparent electrodes 4B,4C if the transparent electrodes 4B, 4C are formed of a hard and brittletransparent conductive oxide. Especially when a substrate formed of anorganic material is used as the transparent substrate 2, the substrateis compressed to increase a deformation amount of the transparentelectrodes 4B, 4C, which is likely to cause a crack or the like.Further, if a conductive polymer equal in softness to the photoelectricconversion layer 5X is used for the transparent electrodes 4B, 4C, thetransparent electrodes 4B, 4C are also scribed at the same time when thepressure with which the surfaces of the transparent electrodes 4B, 4Care surely exposed is applied. Further, if the surfaces of thetransparent electrodes 4B, 4C are exposed, the transparent electrodes4B, 4C come into direct contact with the counter electrodes 6 made ofsilver, aluminum, or the like, which is sometimes likely to causegalvanic corrosion.

On the other hand, if the scribing pressure is decreased in theconventional manufacturing step in order to prevent breakage of thetransparent electrodes 4B, 4C, part of the photoelectric conversionlayer 5X is likely to remain in the groove portions 11A, 11B. If thesoft and viscous photoelectric conversion layer 5X existing on the hardtransparent electrodes 4B, 4C formed of the conductive metal oxide istried to be mechanically scribed, part of the photoelectric conversionlayer 5X is likely to remain in the groove portions 11A, 11B. If part ofthe photoelectric conversion layer 5X remains in the groove portions11A, 11B, electric resistance between the counter electrodes 6A, 6B ofthe photoelectric conversion parts 3A, 3B and the transparent electrodes4B, 4C of the adjacent photoelectric conversion parts 3B, 3C increases,resulting in deterioration of power conversion efficiency.

In the manufacturing method of the photoelectric conversion device 1 ofthe embodiment, the following structure and step are employed. Aconnection step of the photoelectric conversion parts 3 in themanufacturing method of the photoelectric conversion device 1 of theembodiment and the structure of the connection part will be describedwith reference to FIG. 4A to FIG. 4D and FIG. 5A to FIG. 5C. FIG. 4A toFIG. 4D are sectional views illustrating the connection step of thephotoelectric conversion parts 3, and FIG. 5A to FIG. 5C are plane viewsillustrating the connection step of the photoelectric conversion parts3. Note that FIG. 4A to FIG. 4D and FIG. 5A to FIG. 5C illustrate theconnection step of the photoelectric conversion part 3A and thephotoelectric conversion part 3B adjacent thereto. The connection stepof the photoelectric conversion part 3B and the photoelectric conversionpart 3C adjacent thereto is also executed in the same manner. The sameapplies to a case where the photoelectric conversion device 1 has fouror more photoelectric conversion parts 3, and the adjacent photoelectricconversion parts 3 are serially connected in sequence by the same step.

As illustrated in FIG. 4A and FIG. 5A, a conductive layer 12 is formedon the transparent electrode 4B of the photoelectric conversion part 3Bwith which the counter electrode 6A of the photoelectric conversion part3A is electrically connected. The conductive layer 12 functions as aformation region of the groove portion 11A and as a protective layer forthe transparent electrode 4B when the photoelectric conversion layer 5Xis mechanically scribed. Therefore, the conductive layer 12 is formedonly on a region, of the transparent electrode 4B, corresponding to ascribe region of the photoelectric conversion layer 5X. The conductivelayer 12 is formed only on a partial region, of the transparentelectrode 4B, which is adjacent to the transparent electrode 4A. Theconductive layer 12 has a metal material layer formed of metal such asaluminum, gold, platinum, silver, copper, indium, bismuth, lead, tin,zinc, iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten,chromium, and tantalum, or an alloy containing any of these, a carbonmaterial layer of graphene or the like, or a composite material layer inwhich particles and fibers of the aforesaid metal material or carbonmaterial are dispersed in a polymer material (a metal/polymer compositematerial layer or a carbon/polymer composite material layer). Theconductive layer 12 may be a metal material layer in which a pluralityof metal layers are stacked, or may be a film stack of a metal materiallayer and a carbon material layer or the like.

Next, as illustrated in FIG. 4B and FIG. 5B, a first intermediate layer52X and an organic active layer 51X are sequentially formed above thetransparent substrate 2 so as to cover the transparent electrode 4A andthe transparent electrode 4B including the conductive layer 12.Subsequently, as illustrated in FIG. 4C and FIG. 5C, the film stack ofthe first intermediate layer 52X and the organic active layer 51X isscribed along the formation region of the conductive layer 12, wherebythe groove portion 11A is formed. The groove portion 11A is formed bythe mechanical scribing of the film stack of the first intermediatelayer 52X and the organic active layer 51X as previously described. Inthe mechanical scribing of the film stack, a part of the conductivelayer 12 in terms of a thickness direction is scribed out together withthe film stack. The groove portion 11A reaches an inside of theconductive layer 12 and does not reach substantially the transparentelectrode 4B.

By scribing the soft and viscous first intermediate layer 52X andorganic active layer 51X together with a part of the conductive layer 12as previously described, it is possible to prevent the firstintermediate layer 52X and the organic active layer 51X from partlyremaining in the groove portion 11A. The groove portion 11A formed bysuch a mechanical scribing step has a shape reaching an inside(thicknesswise middle portion) of the conductive layer 12 from a surfaceof the film stack of the first intermediate layer 52X and the organicactive layer 51X. The film stack of the first intermediate layer 52X andthe organic active layer 51X is divided into a plurality of parts by thegroove portion 11A reaching the inside of the conductive layer 12, sothat the organic active layers 51A, MB having the first intermediatelayers 52A, 52B are formed so as to correspond to the photoelectricconversion parts 3A, 3B.

Next, as illustrated in FIG. 4D, the second intermediate layers 53A, 53Band the counter electrodes 6A, 6B corresponding to the respectivephotoelectric conversion parts 3A, 3B are sequentially formed on theorganic active layers 51A, 51B. In forming the second intermediate layer53A and the counter electrode 6A of the photoelectric conversion part3A, part (second intermediate layer material) 53 a of the secondintermediate layer 53A and part (counter electrode material) 6 a of thecounter electrode 6A are filled in the groove portion 11A providedbetween the photoelectric conversion part 3A and the adjacentphotoelectric conversion part 3B. In this manner, the counter electrode6A of the photoelectric conversion part 3A is electrically connectedwith the transparent electrode 4B of the adjacent photoelectricconversion part 3B by a connection part 13A having the conductive layer12 and having the second intermediate layer material 53 a and thecounter electrode material 6 a which are filled in the groove portion11A. It should be noted that the second intermediate layer material 53 ain the groove portion 11A is not essential but may be formed only in aregion other than the groove portion 11A.

Considering the function as the formation region (scribing region) ofthe groove portion 11A at the time of the mechanical scribing, theconductive layer 12 is preferably formed of a metal material relativelylow in hardness such as aluminum, gold, platinum, silver, copper,indium, bismuth, lead, tin, zinc, iron, cobalt, or nickel, or a material(first conductive material) in which particles or fibers of a metalmaterial or a carbon material are dispersed in a binder such as a resin.Incidentally, even if the conductive layer 12 is formed of a metalmaterial (second conductive material) relatively high in hardness suchas iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten,chromium, or tantalum, it is more excellent in toughness and so on thanthe conductive metal oxide being the forming material of the transparentelectrode 4, and thus can be scribed without any occurrence of a crackor the like at the time of the mechanical scribing. Therefore, even theconductive layer 12 formed of the second conductive material canfunction as the scribing region at the time of the mechanical scribing.

On the other hand, considering the function as the protective layer forthe transparent electrode 4B, the conductive layer 12 is preferablyformed of the second conductive material relatively high in hardnesssuch as iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten,chromium, and tantalum. Taking these points into consideration, theconductive layer 12 may have: a first conductive layer 121 formed of theaforesaid second conductive material and provided on the transparentelectrode 4B; and a second conductive layer 122 formed of the aforesaidfirst conductive material and provided on the first conductive layer 121as illustrated in FIG. 6.

As described above, the conductive layer 12 may include a plurality ofconstituent layers. The constituent layers of the conductive layer 12each are not limited to the aforesaid metal material layer, and may be acarbon material layer or a material layer in which particles or fibersof a metal material or a carbon material are dispersed in a binder suchas a resin. Out of these plural constituent layers, the constituentlayer in contact with the second transparent electrode (for example, thefirst conductive layer 121) preferably has higher Vickers hardness thanthat of the other constituent layers (for example, the second conductivelayer 122). Employing the conductive layer 12 having such pluralconstituent layers makes it possible to favorably achieve both thefunctions as the scribing region at the time of the mechanical scribingand the protective layer for the transparent electrode 4B. Further, theconductive layer 12 may have three constituent layers or more. Anexample of a specific structure in this case is a film stack having ahigh-hardness constituent layer, a low-hardness constituent layer, and ahigh-hardness constituent layer which are formed sequentially on thetransparent electrode 4B.

The conductive layer 12 forms part of the connection part 13A. That is,the counter electrode 6A of the photoelectric conversion part 3A iselectrically connected with the transparent electrode 4B of the adjacentphotoelectric conversion part 3B via the conductive layer 12.Considering the function of the conductive layer 12 as the electricalconnection part, the conductive layer 12 is preferably formed of metalsuch as aluminum, gold, silver, copper, or molybdenum, or an alloycontaining any of these metals. However, even a conductive materialrelatively low in conductivity (tin, chromium, titanium, or the like, ora material in which particles or fibers of a metal material or a carbonmaterial are dispersed in a binder such as a resin) is usable as theconductive layer 12 if its thickness is made thin within a range notimpairing the functions of the conductive layer 12 as the scribingregion and the protective layer.

According to the photoelectric conversion device 1 of the embodiment andthe manufacturing method thereof, it is possible to prevent part of theorganic active layer 51 and so on from remaining in the groove portion11 without breaking the transparent electrode 4 at the time of themechanical scribing. Therefore, it is possible to improve electricalconnectivity between the adjacent photoelectric conversion parts 3.Specifically, it is possible to reduce connection resistance between thecounter electrode 6A of the photoelectric conversion part 3A and thetransparent electrode 4B of the adjacent photoelectric conversion part3B. An increase of the connection resistance between the photoelectricconversion parts 3 becomes a cause to deteriorate power conversionefficiency of the photoelectric conversion device 1. According to thephotoelectric conversion device 1 of the embodiment and themanufacturing method thereof, it is possible to improve the powerconversion efficiency. In particular, even when the number of theserially connected photoelectric conversion parts 3 is increased, byreducing a probability of an increase of the connection resistancebetween the adjacent photoelectric conversion parts 3, it is possible toenhance the power conversion efficiency as the whole device.

EXAMPLES

Next, examples and their evaluation results will be described.

Example 1

First, a plurality of ITO films each with a 150 nm thickness were formedas transparent electrodes, on a resin film with a 200 μm thicknessformed of polyethylene terephthalate. The plural ITO films were formedaccording to the number of photoelectric conversion parts installed.Next, edge portions of the plural ITO films were coated with silverpaste, followed by drying, whereby conductive layers were formed. Awidth and a thickness of the conductive layers were set to about 0.5 mmand about 5 μm respectively.

Ethoxylated polyethyleneimine (80% ethoxylated (PEIE)) was formed into afilm with an about 1 nm thickness as a transparent electrode-side firstintermediate layer, above the resin film having the plural ITO films andthe conductive layers provided only on partial regions thereof. Next, acoating solution (a coating solution of an organic active layer) inwhich 8 mg PTB7(poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}])and 12 mg PC70BM ([6,6]-phenyl C71 butyric acid methyl ester) weredispersed in 1 mL monochlorobenzene was applied on the firstintermediate layer by a meniscus coating method. A coating condition wasset as follows. A coating head (made of SUS303) with a 303 mm width wasdisposed above the resin film at a 0.88 mm gap. Between the resin filmand the coating head, the coating solution in a 1.38 mL amount wassupplied by using a syringe pump. The coating solution was applied whilethe resin film was moved at a 10 mm/s speed. A coating film was dried at60° C. for 30 minutes, whereby an organic active layer having an about100 nm thickness was formed.

Next, the organic active layer was mechanically scribed along formationregions of the conductive layers, together with part of the conductivelayers, whereby the conductive layers were exposed. As a scribing tool,a general-purpose cutter was used. The cutter was pressed by asuspension mechanism using a spring with an about 1.96 N force and wasscanned in parallel to a longitudinal direction of the conductivelayers, thereby scribing out the organic active layer. At this time,parts of the conductive layers were also scribed out, but the ITO filmswere not exposed. An exposure width of each of the conductive layers wasabout 20 μm.

Thereafter, on the organic active layer, molybdenum trioxide was formedinto a film with an about 5 nm thickness as a counter electrode-sidesecond intermediate layer, and further silver was formed into films withan about 150 nm thickness as counter electrodes. When power conversionefficiency of an organic photovoltaic module obtained in this manner wasmeasured by using a solar simulator with 1.5 G air mass (AM) and 1000W/m² irradiance, the power conversion efficiency was a good value of7.1%.

Example 2

An organic photovoltaic module was fabricated in the same manner as inExample 1 except in the following points. As a transparent substrate, aglass substrate was used. As conductive layers, a film stack of a Moalloy (thickness: 50 nm)/an Al alloy (thickness: 200 mm)/a Mo alloy(thickness: 50 nm) was used. The film stack was patterned by aphotolithography method. In a mechanical scribing step, a suspensionmechanism using a spring with an about 4.9 N force was used. In themechanical scribing step, part of the film stack was also scribed out,but ITO films were not exposed. An exposure width of the film stack wasabout 20 μm. When power conversion efficiency of the organicphotovoltaic module obtained in this manner was measured in the samemanner as in Example 1, the power conversion efficiency was a good valueof 7.5%.

Comparative Example 1

An organic photovoltaic module was fabricated in the same manner as inExample 1 except that conductive layers were not formed on transparentelectrodes. When a pressing force of a cutter in a mechanical scribingstep was set to about 1.96 N as in Example 1, ITO films cracked andbroken pieces were produced. When the pressing force of the cutter wasup to about 1.18 N, a crack was confirmed in the ITO films. When thepressing force of the cutter was decreased to about 0.98 N, there was nobroken piece of the ITO films. However, when power conversion efficiencyof this organic photovoltaic module was measured in the same manner asin Example 1, the power conversion efficiency was 3.5% and thus inferiorto that of Example 1. It is inferred that this is because, out ofmeasurement values, series resistance Rs is larger as compared withExample 1 and accordingly an organic active layer partly remains inscribe grooves, and this serves as resistance and does not allowsufficient series connection between cells.

Comparative Example 2

An organic photovoltaic module was fabricated in the same manner as inExample 2 except that conductive layers were not formed on transparentelectrodes. When a pressing force of a cutter in a mechanical scribingstep was set to about 4.9 N as in Example 2, there was no broken pieceof ITO films. However, when power conversion efficiency of this organicphotovoltaic module was measured in the same manner as in Example 2, thepower conversion efficiency was 6.5% and thus inferior to that ofExample 2. It is inferred that this is because, out of measurementvalues, series resistance Rs is larger as compared with Example 2 andaccordingly an organic active layer partly remains in scribe grooves,and this serves as resistance and does not allow sufficient seriesconnection between cells. Further, it was confirmed that an exposurewidth of a film stack was about 10 μm at a starting position of thescribing and was narrower than that in Example 2. An exposure width ofthe film stack at an end position of the scribing was increased to about25 μm, and abrasion of a blade edge of a cutter was confirmed.Accordingly, even when the pressing force of the cutter was adjusted,compatibility of power conversion efficiency and lifetime of the cutterwas inferior as compared with Example 2.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The inventions described in the accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the inventions.

What is claimed is:
 1. A photoelectric conversion device comprising: a transparent substrate; a first photoelectric conversion part including a first transparent electrode provided on the transparent substrate, a first organic active layer disposed on the first transparent electrode, and a first counter electrode disposed on the first organic active layer; a second photoelectric conversion part including a second transparent electrode disposed on the transparent substrate adjacently to the first transparent electrode and electrically insulated from the first transparent electrode, a conductive layer formed on a partial region of the second transparent electrode, the partial region being adjacent to the first transparent electrode, a second organic active layer disposed on the second transparent electrode, and a second counter electrode disposed on the second organic active layer; and a connection part including a groove formed from a surface of the second organic active layer to reach an inside of the conductive layer and a part of the first counter electrode filled in the groove, and which electrically connects the first counter electrode and the second transparent electrode via the conductive layer.
 2. The photoelectric conversion device of claim 1, wherein the conductive layer has at least one layer selected from a metal material layer containing at least one element selected from a group consisting of aluminum, gold, platinum, silver, copper, indium, bismuth, lead, tin, zinc, iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten, chromium, and tantalum, a carbon material layer, a metal/polymer composite material layer in which powder of the metal element is dispersed in a polymer material, and a carbon/polymer composite material layer in which powder of the carbon material is dispersed in a polymer material.
 3. The photoelectric conversion device of claim 2, wherein the conductive layer includes a plurality of constituent layers selected from the metal material layer, the carbon material layer, the metal/polymer composite material layer, and the carbon/polymer composite material layer, and the constituent layer in contact with the second transparent electrode out of the plural constituent layers is higher in Vickers hardness than the other constituent layer.
 4. The photoelectric conversion device of claim 1, wherein the conductive layer includes: a first conductive layer containing at least one element selected from a group consisting of iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten, chromium, and tantalum and provided on the second transparent electrode; and a second conductive layer containing at least one element selected from a group consisting of aluminum, gold, platinum, silver, copper, indium, bismuth, lead, tin, and zinc, and provided on the first conductive layer.
 5. The photoelectric conversion device of claim 1, wherein the first and second transparent electrodes each contain at least one selected from indium oxide, zinc oxide, tin oxide, indium tin oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, aluminum-doped zinc oxide, indium-zinc oxide, indium-gallium-zinc oxide, poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate), and graphene.
 6. The photoelectric conversion device of claim 1, wherein the first and second photoelectric conversion parts each include: a first intermediate layer disposed between the transparent electrode and the organic active layer; and a second intermediate layer disposed between the organic active layer and the counter electrode, and wherein the groove penetrates from a surface of the organic active layer through the first intermediate layer to reach the inside of the conductive layer.
 7. A manufacturing method of a photoelectric conversion device, comprising: forming, on a transparent substrate, a first transparent electrode and a second transparent electrode adjacent to the first transparent electrode and electrically insulated from the first transparent electrode; forming a conductive layer on a partial region of the second transparent, the partial region being adjacent to the first transparent electrode; forming an organic active layer above the transparent substrate so as to cover the first transparent electrode and the second transparent electrode; scribing the organic active layer along a formation region of the conductive layer to form a groove reaching an inside of the conductive layer from a surface of the organic active layer; and forming a first counter electrode and a second counter electrode on the organic active layer divided by the groove so as to correspond to the first transparent electrode and the second transparent electrode, wherein a part of the first counter electrode is filled in the groove to electrically connect the first counter electrode and the second transparent electrode via the conductive layer.
 8. The manufacturing method of claim 7, wherein the groove is formed by mechanical scribing of the organic active layer.
 9. The manufacturing method of claim 7, wherein the conductive layer has at least one layer selected from a metal material layer containing at least one element selected from a group consisting of aluminum, gold, platinum, silver, copper, indium, bismuth, lead, tin, zinc, iron, cobalt, nickel, titanium, zirconium, molybdenum, tungsten, chromium, and tantalum, a carbon material layer, a metal/polymer composite material layer in which powder of the metal element is dispersed in a polymer material, and a carbon/polymer composite material layer in which powder of the carbon material is dispersed in a polymer material.
 10. The manufacturing method of claim 7, wherein the first and second transparent electrodes each contain at least one selected from indium oxide, zinc oxide, tin oxide, indium tin oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, aluminum-doped zinc oxide, indium-zinc oxide, indium-gallium-zinc oxide, poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonic acid), and graphene 